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After suffering from airspeed decay with higher than expected static air temperatures and with loss of aircraft control imminent, the PIC of a westwind 11 corp jet left FL430 in conflict with other traffic at FL410 on frequency with ZLC, ut.
| Attributes | |
| ACN | 562657 |
| Time | |
| Date | 200210 |
| Day | Wed |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : zlc.artcc |
| State Reference | UT |
| Altitude | msl bound lower : 41000 msl bound upper : 42600 |
| Environment | |
| Flight Conditions | VMC |
| Weather Elements | Turbulence |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zlc.artcc tower : pit.tower |
| Operator | general aviation : corporate |
| Make Model Name | Israel Aircraft Undifferentiated or Other Model |
| Operating Under FAR Part | Part 91 |
| Flight Phase | cruise : enroute altitude change |
| Route In Use | enroute : direct |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : zlc.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : corporate |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 128 flight time total : 8500 flight time type : 550 |
| ASRS Report | 562657 |
| Person 2 | |
| Affiliation | company : corporate |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude conflict : airborne less severe inflight encounter : turbulence inflight encounter other non adherence : clearance non adherence : required legal separation non adherence : published procedure other anomaly other anomaly other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : temp/airspeed gauge other flight crewa other flight crewb |
| Resolutory Action | controller : issued advisory flight crew : regained aircraft control flight crew : declared emergency |
| Miss Distance | horizontal : 24000 vertical : 1500 |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance Aircraft ATC Human Performance Weather |
| Primary Problem | Weather |
| Air Traffic Incident | Pilot Deviation |
Narrative:
While en route from bhm to bfi at FL410, we were near jackson, wy, when we requested FL430. We were then instructed by ATC to climb to FL430. As the aircraft climbed to FL430, we began to encounter light turbulence. Over the next approximately five mins, the aircraft started to slowly decelerate and the turbulence continued to increase. The captain then advised me to request a lower altitude, which I did. We were advised it would be five mins before we could descend due to conflicting traffic. The turbulence continued to get worse and the airspeed continued to decelerate. The captain again instructed me to ask for a lower altitude. I again requested a lower altitude from ATC and was told to stand by, as there was conflicting traffic. I then observed the traffic, an airliner at our 11 O'clock position, and advised ATC we had the traffic in sight. ATC then advised us we could descend when we had 5 mile separation. The captain advised ATC we needed to descend right away and we could accept a vector in any direction. The turbulence was now moderate and the airspeed was continuing to decrease. The captain had increased power to maximum continuous power to maintain altitude and was having an increasingly difficult time maintaining positive control of the aircraft. ATC advised us the only way we could descend was if we declare an emergency. I stated, 'ok, we are descending' and we vacated FL430. ATC instructed us to descend after we were at FL426. The conflicting traffic was in sight and was no factor, as we started our descent. It was the captain's opinion, and I concur, that the aircraft was becoming increasingly hard to control and the conflicting traffic was not a factor when we started the descent. The chain of events contributing to in-flight emergency were: 1) decaying airspeed 2) increasingly moderate turbulence 3) higher than normal isa (indicated static air temperature) which decreased the aircraft's performance. The human performance considerations were: 1) we should have been more informative to ATC as to the problems we were encountering. 2) we should have made the decision earlier to start the descent. 3) I should have been more clear and concise with ATC that we were declaring an emergency as we started our descent.
Original NASA ASRS Text
Title: AFTER SUFFERING FROM AIRSPD DECAY WITH HIGHER THAN EXPECTED STATIC AIR TEMPS AND WITH LOSS OF ACFT CTL IMMINENT, THE PIC OF A WESTWIND 11 CORP JET LEFT FL430 IN CONFLICT WITH OTHER TFC AT FL410 ON FREQUENCY WITH ZLC, UT.
Narrative: WHILE ENRTE FROM BHM TO BFI AT FL410, WE WERE NEAR JACKSON, WY, WHEN WE REQUESTED FL430. WE WERE THEN INSTRUCTED BY ATC TO CLIMB TO FL430. AS THE ACFT CLIMBED TO FL430, WE BEGAN TO ENCOUNTER LIGHT TURB. OVER THE NEXT APPROX FIVE MINS, THE ACFT STARTED TO SLOWLY DECELERATE AND THE TURB CONTINUED TO INCREASE. THE CAPT THEN ADVISED ME TO REQUEST A LOWER ALT, WHICH I DID. WE WERE ADVISED IT WOULD BE FIVE MINS BEFORE WE COULD DESCEND DUE TO CONFLICTING TFC. THE TURB CONTINUED TO GET WORSE AND THE AIRSPD CONTINUED TO DECELERATE. THE CAPT AGAIN INSTRUCTED ME TO ASK FOR A LOWER ALT. I AGAIN REQUESTED A LOWER ALT FROM ATC AND WAS TOLD TO STAND BY, AS THERE WAS CONFLICTING TFC. I THEN OBSERVED THE TFC, AN AIRLINER AT OUR 11 O'CLOCK POSITION, AND ADVISED ATC WE HAD THE TFC IN SIGHT. ATC THEN ADVISED US WE COULD DESCEND WHEN WE HAD 5 MILE SEPARATION. THE CAPT ADVISED ATC WE NEEDED TO DESCEND RIGHT AWAY AND WE COULD ACCEPT A VECTOR IN ANY DIRECTION. THE TURB WAS NOW MODERATE AND THE AIRSPD WAS CONTINUING TO DECREASE. THE CAPT HAD INCREASED PWR TO MAX CONTINUOUS PWR TO MAINTAIN ALT AND WAS HAVING AN INCREASINGLY DIFFICULT TIME MAINTAINING POSITIVE CTL OF THE ACFT. ATC ADVISED US THE ONLY WAY WE COULD DESCEND WAS IF WE DECLARE AN EMER. I STATED, 'OK, WE ARE DESCENDING' AND WE VACATED FL430. ATC INSTRUCTED US TO DESCEND AFTER WE WERE AT FL426. THE CONFLICTING TFC WAS IN SIGHT AND WAS NO FACTOR, AS WE STARTED OUR DESCENT. IT WAS THE CAPT'S OPINION, AND I CONCUR, THAT THE ACFT WAS BECOMING INCREASINGLY HARD TO CTL AND THE CONFLICTING TFC WAS NOT A FACTOR WHEN WE STARTED THE DESCENT. THE CHAIN OF EVENTS CONTRIBUTING TO INFLT EMER WERE: 1) DECAYING AIRSPD 2) INCREASINGLY MODERATE TURB 3) HIGHER THAN NORMAL ISA (INDICATED STATIC AIR TEMP) WHICH DECREASED THE ACFT'S PERFORMANCE. THE HUMAN PERFORMANCE CONSIDERATIONS WERE: 1) WE SHOULD HAVE BEEN MORE INFORMATIVE TO ATC AS TO THE PROBS WE WERE ENCOUNTERING. 2) WE SHOULD HAVE MADE THE DECISION EARLIER TO START THE DESCENT. 3) I SHOULD HAVE BEEN MORE CLR AND CONCISE WITH ATC THAT WE WERE DECLARING AN EMER AS WE STARTED OUR DESCENT.
Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.